Compositions comprising oxytetracycline are well known. For example, U.S. Pat. No. 3,017,232 describes compositions comprising oxytetracycline salts and polyhydric aliphatic alcohols. U.S. Pat. No. 4,020,162 describes compositions comprising oxytetracycline, magnesium chloride, polyethylene glycol, a base, preservatives, and a buffer system. However, the maximum oxytetracycline concentration which can be achieved in these compositions is only approximately 12% by weight of the total composition.
U.S. Pat. No. 4,386,083 describes compositions comprising oxytetracycline, glycerol formal, and magnesium chloride, magnesium acetate, or magnesium oxide. This composition is described as being able to contain from greater than about 15% by weight to about 35% by weight oxytetracycline.
U.S. Pat. No. 4,081,528 describes an aqueous composition comprising tetracycline, magnesium oxide, and 2-pyrrolidone as a co-solvent.
It is the purpose of this invention to provide an aqueous oxytetracycline composition comprising polyethylene glycol which can contain up to about 30% by weight oxytetracycline, has good clarity and has an acceptable viscosity.